As set forth in U.S. Pat. No. 3,378,068 to J. S. Page, Jr. a well flow control valve is shown which allows annular fluids to pass from the annulus of a well to the tubing throughbore. Such a device utilizes a "sliding sleeve" valve carried by the tubing. The sleeve portion of the valve is actuated from an open or closed position by use of a hydraulically actuated device that is lowered by a wire line downwardly through the tubing throughbore. The valve sleeve contains seals at either end to effectively seal the sliding valve in either the open or the closed position.
Such a sliding sleeve valve is subject to erosion and/or corrosion by the well fluids that pass through its ports with the subsequent requirement of replacement of the seals used by the valve, and/or the replacement of the entire sliding sleeve valve itself. Such a replacement operation requires that the entire tubing string carrying the valve be removed from the well, to allow access to the valve for the required maintenance and repairs. The well must be "shut-in" during this repair, which causes significant loss of revenues in the case of a producing oil or gas well.
A valve need be developed therefore whereby the entire tubing string need not be removed from the well in order to effectively repair and/or replace the valve components subjected to erosion and/or corrosion. In particular the seals on such a valve that isolate one fluid flow zone from another need to be easily replaceable without removal of the entire tubing string.
Such a valve should also be designed so that alternative fluid flow paths may be used between different fluid flow zones of the well, without requiring the retrieval of the entire tubing string in order to change the sliding sleeve valve which has only one set flow path. In other words, the operator of a well should be able to easily change the fluid flow patterns throughout the length of the entire well without the requirement for extensive tubular goods removal and replacement.